This invention relates generally to a passenger carrying vehicle and particularly to a self-propelled vehicle especially used to transport mobility impaired passengers such as a wheelchair bound individual between an airport gate at ground level and an aircraft doorway at a different elevation.
In the past there have been various vehicles designed to transport disabled passengers to and from aircraft. One such design is disclosed in U.S. Pat. No. 4,176,732, issued to Robert A. Nordskog. The Nordskog design is an enclosed cabin which can be moved and elevated by a modified conventional forklift vehicle. The forklift vehicle controls are relocated to the interior of the cabin so that the operator is inside along with the passenger. Although the cabin has a cushioned bumper around its lower margins, the operator must take great care in positioning the cabin against the aircraft to prevent damage to the aircraft skin.
Another design is disclosed in U.S. Pat. No. 5,205,697 issued to Getty et al. This design includes a self-propelled steerable vehicle and a separate compartment for the operator containing steering, braking, motive and lift assembly controls. The operator's position is below and to the rear of the passenger compartment which allows the operator visual control of the approach to aircraft's fuselage. An extendable ramp from the wheelchair platform is used to extend into the open doorway of the aircraft. Again, there is no provision for automatically stopping forward movement of the vehicle when in comes in contact with the aircraft.
U.S. Pat. No. 4,971,510 issued to Houle discloses another design wherein there is a cab and a separate holding compartment for persons in wheelchairs. Both the holding compartment and the cab for the operator are elevated and lowered by the operator of the unit. An extendable platform extends from the holding compartment to form a bridge between the cab and the aircraft door. An automatic control for the vehicle motor restricts movement of the vehicle frame to a slow speed whenever the cab is raised above the ground level, thereby permitting the frame and the vehicle to be "inched" into position on the doorsill of the aircraft.
U.S. Pat. No. 5,096,018 issued to Dickenson, discloses an apparatus for securing a "man basket" or cage to the tines of a fork-lift.
U.S. Pat. No. 4,662,809 issued to Sturtz et al discloses an automatic level device forming a part of a motor platform to align a lift device with the aircraft. An umbilical cord with liquid mercury is used to adjust the level of the platform an align the platform with the aircraft.
U.S. Pat. No. 5,105,915 issued to Gary discloses a wheelchair lift particularly for use as an adjustable seating arrangement for people in wheelchairs.
U.S. Pat. No. 5,154,569 issued to Eryou et al discloses a lift device for transferring wheelchair passengers to commuter aircraft which includes a bridge formed between the platform and the door of the aircraft together with stairs that can be used by able persons to board the aircraft.
A particular problem with all of the conventional passenger lift vehicle designs is that substantial damage to the aircraft can result if the operator positions the device against the aircraft fuselage with too much force. Alternatively, damage can result to the aircraft if the vehicle is maneuvered forward when the cabin or other platform is already positioned beside the aircraft. Accordingly, there is a need for a vehicle which automatically senses the presence of the aircraft fuselage and prevents forward movement of the vehicle upon contact therewith.